Ultrastructural studies in human polymyositis

Inflammatory cardiomyopathy. The controversy of diagnosis and management

This article reviews the theories regarding the causes of lymphocytic myocarditis, including viral and immunologic (cellular versus humoral) causes. Also covered is the relationship of dilated cardiomyopathy to myocarditis, the familial predilection for dilated cardiomyopathy in some cases, shortcomings of the various modalities for diagnosing lymphocytic myocarditis, and the occurrence of lymphocytic myocarditis in association with systemic illnesses. Lastly, treatment options for myocarditis are explored.

Inclusion body myositis: a chronic persistent mumps myositis?

Among the generalized chronic idiopathic inflammatory myopathies, inclusion body myositis (IBM) has emerged as a clinico-pathologic variant during the past two decades. It occurs primarily in elderly persons (in approximately the sixth decade of life), but young adults (in approximately the second decade of life) may also be affected. Slowly progressive weakness of distal as well as proximal muscle groups in IBM is usually not associated with skin rash, malignancy or collagen-vascular disease, and is refractory to treatment with steroids or other immunosuppressants. Exceptions to each of these general rules have been found. Muscle biopsy and electromyography may suggest a neurogenic process mixed with myopathic features. Rimmed vacuoles with basophilic granules in cryostat sections stained with hematoxylin-eosin are strongly suggestive of IBM if accompanied by the histopathologic triad of polymyositis. The presence of eosinophilic intranuclear or cytoplasmic inclusions in affected myofibers is further suggestive of IBM. The ultimate diagnosis, however, depends on ultrastructural demonstration of characteristic microtubular filaments resembling the nucleocapsids of the paramyxovirus group. Recent reports of immunostaining of the inclusions for mumps virus antigen strongly suggest a chronic persistent mumps virus infection as the cause of IBM. IBM is considered to be pathologically related to both distal myopathy (DM) and oculopharyngeal muscular dystrophy (OPMD).

Mononuclear cells in myopathies: quantitation of functionally distinct subsets, recognition of antigen-specific cell-mediated cytotoxicity in some diseases, and implications for the pathogenesis of the different inflammatory myopathies

Monoclonal antibodies reactive for B cells, T cells, T-cell subsets, killer (K) and natural killer (NK) cells, and the Ia antigen were used to analyze mononuclear cell subsets in scleroderma (SD), dermatomyositis (DM), polymyositis (PM), inclusion body myositis (IBM), Duchenne dystrophy (DD), and normal muscle. The analysis, which was quantitative, was performed according to diagnosis and site of accumulation. Cells at perivascular, perimysial, and endomysial sites of accumulation, and cells focally surrounding and invading nonnecrotic muscle fibers, were analyzed separately. Individual antigens were localized in 2-micron serial sections, or multiple antigens were demonstrated in a given section by sequential paired immunofluorescence. The latter approach allowed the identification of the cell phenotypes in which functional properties are defined by multiple markers, e.g., T8+ and T4+ cells that are either activated or not activated, T8+ cells that are either cytotoxic or suppressor T cells, and K/NK cells of varying maturity and killing capability. The interactions of inflammatory cells of various types with each other and the muscle fiber were further investigated by immunoelectron microscopy. In SD, the findings provide evidence for a cell-mediated immune effector response against a connective tissue and/or vascular element. In DM, the effector response appears to be predominantly humoral. In PM and IBM (but not in DM or SD), there is invasion and destruction of nonnecrotic muscle fibers by cytotoxic T cells, with or without accompanying macrophages. Because T-cell-mediated injury is antigen- and major histocompatibility complex-restricted, clones of T cells must have been sensitized previously to a muscle fiber-associated surface antigen. The identity of the putative antigen(s) remains an important, unsolved question.

HLA-DR expression, T lymphocyte phenotypes, OKM1 and OKT9 reactive cells in inflammatory myopathy

Frozen muscle biopsy sections from 13 patients with inflammatory myopathy and from four healthy volunteers were characterized with a double immunohistochemical staining technique, utilizing a panel of antisera to cell surface antigens. The technique enables simultaneous visualization of HLA-DR reactive cells and other cell types, i.e., T lymphocytes. In inflammatory myopathy, large numbers of HLA-DR reactive "macrophage/dendritic" cells were shown. Almost all other inflammatory cells and endothelial cells also expressed HLA-DR, as did the sarcolemma in the vicinity of inflammatory foci. Large numbers of T lymphocytes were detected by alphaLeu-1 antibodies. In most instances, Leu-3a reactive T "helper" lymphocytes dominated over alphaLeu-2a reactive T "suppressor/cytotoxic" lymphocytes. Many T lymphocytes of both phenotypes appeared in close contact with HLA-DR expressing non-T cells. OKM1 and OKT9 antibodies, labeling macrophages and "proliferating" cells, respectively, were common among inflammatory cells. The findings provide basic data that are important for the understanding of inflammatory myopathy.

Inclusion body myositis: a case with associated collagen vascular disease responding to treatment

Patients with inclusion body myositis demonstrate characteristic histological and electronmicroscopical abnormalities in muscle and are generally considered refractory to treatment. A patient with inclusion body myositis is described with evidence of associated autoimmune disease, who responded to steroids.

Monoclonal antibody analysis of mononuclear cells in myopathies. I: Quantitation of subsets according to diagnosis and sites of accumulation and demonstration and counts of muscle fibers invaded by T cells

In 76 muscle specimens (normal controls, 9; Duchenne dystrophy, 11; scleroderma, 11; dermatomyositis, 13; polymyositis, 15; inclusion body myositis, 17), mononuclear cells were analyzed at perivascular, perimysial, and endomysial sites of accumulation. Monoclonal antibodies reactive for B cells, T cells, T cell subsets, killer (K) or natural killer (NK) cells, and the Ia antigen were used for cell typing. Macrophages were identified by the acid phosphatase reaction. Few extravascular mononuclear cells occurred in normal muscle. In all inflammatory myopathies, a mixed exudate of T cells, B cells, and macrophages was present. Mature K/NK cells were rare in all diseases. In dermatomyositis, polymyositis, and inclusion body myositis, there was a positive gradient for T cells, T8+ cells, and activated T cells and a negative gradient for B cells and T4+ cells between perivascular and endomysial sites. In scleroderma the predominant perimysial exudate consisted mostly of T cells and macrophages. The percentage of B cells at all sites, and the T4+/T cell ratio in the endomysium, were significantly higher in dermatomyositis than in the other diseases. In polymyositis and inclusion body myositis, the endomysial exudate contained a large number of T cells, T8+ cells, and activated T cells but only sparse B cells. T cells accompanied by macrophages focally surrounded and invaded nonnecrotic fibers in polymyositis and inclusion body myositis. Rare fibers in Duchenne dystrophy and a very few fibers in dermatomyositis and scleroderma were similarly affected. We infer that (1) T-B, T-T, and T-macrophage cooperativities are likely to exist in muscle in different myopathies; (2) T cell-mediated fiber injury plays a role in polymyositis and inclusion body myositis; (3) T cell-mediated fiber injury can also occur in inherited diseases, such as Duchenne dystrophy; and (4) a local humoral response may occur in muscle in dermatomyositis and possibly in polymyositis and inclusion body myositis.

Adult-onset mixed myopathy with nemaline rods, minicores, and central cores: a muscle disorder mimicking polymyositis

A woman, aged 75 years, presented with a 15-year history of progressive, generalized, painful muscle weakness and wasting. Clinical and laboratory investigation revealed a sporadic muscle disorder. Muscle biopsy showed a mixed pattern of nemaline myopathy with minicores and central cores and severe atrophy of type-1 and type-2 fibers. A trial of immunosuppressive treatment did not improve her condition, which clinically mimicked chronic progressive polymyositis. Mixed myofibrillar myopathies of this type have so far only been described among the group of congenital myopathies.

Intranuclear inclusions in muscle, nervous tissue, and adrenal gland

A 30-year-old man had had chronic progressive wasting and weakness of muscles for 17 years. A muscle biopsy 5 years prior to death revealed myopathic changes were rimmed vacuoles and intranuclear inclusions which corresponded to "inclusion body myositis". At autopsy, intranuclear inclusions were observed in neurons, oligodendroglia, and in parenchymal cells of the adrenal medulla. Ultrastructurally, the inclusions in muscles, nervous tissue, and adrenal medulla were identical and consisted of abnormal tubulolinear structures measuring 10-20 nm in diameter. Similar inclusions have been reported in muscles with "inclusion body myositis" and in the nervous system with "neuronal intranuclear hyaline inclusion disease", respectively. Absence of clinical symptoms related to the CNS and adrenal gland, and well-preserved parenchymal cells in these organs of our patient suggest a benign nature of the disease except in the muscular system. Attempts to isolate a virus from the brain were fruitless . This patient may serve to connect both diseases in muscles and the nervous system, and to disclose the etiology of these inclusions.

Inflammatory myopathy: a review of etiologic and pathogenetic factors

Human idiopathic inflammatory myopathy is an acquired disorder with an annual incidence of two to five cases per million. A genetic influence on host susceptibility may also play a role. With the marked heterogeneity of the disease one of the major challenges is to identify subsets that might share a more uniform pathogenesis and manifest a less diverse profile of clinical findings, histopathological abnormalities, and natural history. Dermatomyositis can be distinguished by clinical appearance and pathological changes, but the recognition of additional disease subsets remains very inexact. Current evidence suggests that dermatomyositis occurs as a result of a vasculopathy, but immune mechanisms involved in other categories of idiopathic inflammatory myopathy may also involve cell-mediated immunity and possibly multiple mechanisms. Even though viral-induced muscle inflammation occurs in humans, there is no convincing evidence for a viral cause of idiopathic inflammatory myopathy. Experimental allergic myositis may be produced by the injection of animals with skeletal muscle homogenates and complete Freund's adjuvant, but the myositogenic factor is unknown and the parallels between experimental allergic myositis and human idiopathic inflammatory myopathy are limited.

Inclusion body myositis. Clinical, biological and ultrastructural study

A 48-year-old patient presented for the past 4 years an amyotrophy of the quadriceps and moderate involvement of the truncal and pelvic girdle muscles. The CK level was elevated (10 times the normal rate) and the EMG revealed a fibrillation pattern on relaxation, myotonic bursts on needle insertion and reduced activity during contraction. The histological study of the muscle biopsy showed nuclear cytoplasmic inclusion bodies and pseudo-myelinic membranes. The case was classified in the inclusion body myositis group. Analysis of the other published cases underlines the variety of the clinical, biological and electromyographical aspects and abnormalities.

Inclusion body myositis

The histochemical and ultrastructural study of muscle biopsies of two patients with a chronic muscle weakness and wasting showed particular changes in muscle fibers: (1) peripheral lined vacuoles, containing whorls of membranes and cytoplasmic debris; (2) collections of intranuclear and intrasarcoplasmic tubular filaments (16-18 nm in external diameter and 6.5 nm in inner diameter). These changes are characteristic of a rare muscle disorder termed inclusion body myositis; its individuality is favoured by the present study. The resemblance of the tubular filaments to myxovirus nucleocapsid has been suggested by various authors but attempts to isolate the virus were unsuccessful in several reported cases as well as in those here presented. This does not exclude a viral origin of the disease. The similarity of the tubular filaments to thick myofilaments has been invoked by others, but has not been demonstrated. At the present the nature of the abnormal filaments remains unknown.

An electron microscopic study of childhood dermatomyositis

Muscle biopsies from 12 patients with a typical clinical picture of dermatomyositis have been examined by electron microscopy. Endothelial cells of intramuscular blood vessels, their basal lamina, pericytes, muscle fibers, and satellite cells show degenerative or regenerative alterations. In nine patients, tubular arrays were noted in the cisterns of endoplasmic reticulum of endothelial cells, pericytes, lymphocytes, macrophages and satellite cells. Other types of inclusions were also observed. The pathogenesis of the disease is discussed.

Acute viral polymyositis with predominant diaphragm involvement

A 20-month-old mentally retarded girl developed an acute upper respiratory infection, followed by breathing difficulties, leading to death. Picorna virus-like particles were demonstrated in a mildly affected quadriceps femoris muscle biopsy, while the necropsy findings demonstrated an acute polymyositis with predominant diaphragm involvement. The mental retardation was due to micropolygyria of the brain. Initial respiratory difficulties are an unknown feature of polymyositis. In this case the upper respiratory infection, possibly caused by a Coxsackie B2, is evoked as responsible for this unusual distribution of the acute viral polymyositis.